Glass-capillary microfluidic devices have recently enabled formation of highly monodisperse emulsions with a rich array of droplet morphologies, such as those disclosed in U.S. Provisional Patent Application Ser. No. 60/920,574, filed Mar. 28, 2007, entitled “Multiple Emulsions and Techniques for Formation,” by Chu, et al., incorporated herein by reference. Such devices exhibit chemical robustness and precise control.
An emulsion is a fluidic state which exists when a first fluid is dispersed in a second fluid that is typically immiscible or substantially immiscible with the first fluid. Examples of common emulsions are oil in water and water in oil emulsions. Multiple emulsions are emulsions that are formed with more than two fluids, or two or more fluids arranged in a more complex manner than a typical two-fluid emulsion. For example, a multiple emulsion may be oil-in-water-in-oil (“o/w/o”), or water-in-oil-in-water (“w/o/w”). Multiple emulsions are of particular interest because of current and potential applications in fields such as pharmaceutical delivery, paints and coatings, food and beverage, chemical separations, and health and beauty aids.